The heart attack, Cheney's fourth, presented an unexpected credibility crisis for the campaign of Texas Gov. George W. Bush as it battled over the recount of votes in Florida. Early in the day Bush told reporters that Cheney had not had a heart attack, and did not mention that his running mate had had surgery, even though Cheney aides said the Bush campaign had been told about the operation.

Bush did not know about the heart attack until later tests confirmed it, aides said.

Cheney's health was an issue during the presidential campaign because of his three previous heart attacks and quadruple bypass surgery he underwent in 1988. Bush assured the nation that Cheney would still be able to serve, and Cheney said the same Wednesday night during a telephone call to CNN's "Larry King Live" show.

"I feel good and everything's looking good," Cheney said. "I should be out in a day or two."

Asked if the heart attack might impede his ability to serve as vice president, Cheney said there was "no doubt about my serving. All we have to do now is get elected."

Dr. Alan Wasserman, a hospital physician who briefed reporters, described the heart attack as "very slight." He said the former defense secretary's chances of a full recovery were "excellent" after an operation in which doctors inserted a stainless steel stent into the blocked artery to keep it clear.

News of Cheney's heart attack emerged gradually during the day through news conferences.

"Dick Cheney is healthy. He did not have a heart attack," Bush said at a noon news conference in Austin. Bush said he had spoken on the phone with his running mate, and Cheney "sounded strong and vibrant."

Though Cheney Chief of Staff Kathleen Shanahan said the Bush campaign had been informed before the governor's news conference about the medical procedures performed on Cheney, Bush did not mention the operation.

About the same time Bush spoke, a blood test performed on Cheney confirmed that he had in fact suffered a heart attack, doctors later said. But Cheney's medical team did not disclose the heart attack to reporters at a 2:30 p.m. briefing.

Instead, in a statement that Wasserman said was drafted in concert with Cheney's family, Wasserman stressed that an initial test indicated the candidate had not suffered a heart attack. He apologized for the omission in an early evening briefing after the hospital and Bush campaign were besieged by inquiries.

For weeks after the Texas governor named Cheney as his running mate, numerous news organizations including the Tribune requested detailed medical information on Cheney. The campaign released two letters from Cheney's doctors, describing general medical problems but pronouncing Cheney "in excellent health."

Cheney, who was in charge of vetting potential Bush running mates, has a history of chronic heart disease. He suffered his first heart attack at age 37 and had three attacks by the time he turned 48. In addition, the doctors said Cheney had a history of high cholesterol and several "minor episodes" of gout, a condition associated with heart disease.

He went to the emergency room about 4:30 a.m. Wednesday after being awoken by chest pains. Doctors said that, although an initial test did not indicate a heart attack, further tests showed a blocked artery in his heart and confirmed a heart attack.

By 10:30 a.m., doctors were performing an angioplasty to unblock the artery. They then inserted the stent to help prevent the artery from closing again. The procedure is common for patients with a history of heart disease and chest pain, experts said.

The operation usually involves inserting a catheter into the patient's leg and threading it into the affected coronary artery. Doctors then perform the angioplasty, inflating a tiny balloon to reopen the narrow artery. Finally, the stent, a stainless steel mesh tube, is expanded and embedded into the artery's walls to help prevent them from closing again. Such a procedure normally is performed when the affected coronary artery has a narrowing of more than 70 percent.

Cheney's artery was 90 percent to 95 percent blocked, said Dr. Jonathan Reiner, who performed the surgery.

Cheney suffered "an extremely small amount" of new heart damage as a result of the attack, Reiner said. He should be able to leave the hospital in two or three days and soon resume his normal duties, doctors added.

"His prognosis is excellent at this point in time. I would expect that he should be able to get back to normal functioning and normal activity within a few weeks, at the very most," Wasserman said.

Wasserman said he did not believe Cheney's illness was related to stress from the campaign.

Bush said he would continue consulting with Cheney and made it clear that he wasn't looking for a replacement.